Westcountry farming leaders said it is "absolutely vital" the Government allows fruit pickers from outside Europe into the country to help keep the industry afloat.
Farmers want Whitehall to allow fruit pickers into Britain as they expect Romanians and Bulgarians to turn down the role in favour of other jobs.
Nearly 22,000 fruit pickers are employed each year under the seasonal agricultural workers scheme – an initiative targeted exclusively at Romanians and Bulgarians.
Temporary curbs were imposed on the two groups in 2005 to protect the British labour market.
But farmers in Devon and Cornwall now fear that when access restrictions to Britain are lifted for the two countries at the end of the year, Romanians and Bulgarians will ditch fruit picking in favour of other jobs.
Ian Johnson, NFU spokesman for the South West, said the dire weather during the 2012 season has more than demonstrated the challenges that growers face in producing such perishable crops.
He added: "But, while we'll never control what nature throws at us, one burden we can prevent hanging over our heads is the prospect of not having enough labour available on farm after the current SAWS arrangements expire in 2013.
"It is absolutely vital that work starts now on securing a successor to SAWS, particularly in an industry like horticulture where growers are always planning a few years ahead.
"The NFU – with the backing of several labour providers – has already submitted proposals on a successor to SAWS, which government is considering.
"We have also had constructive discussions with the Department for Work and Pensions to discuss possible incentives to attract more of the resident workforce into the horticulture sector.
"With the current high level of unemployment our industry must be seen to do everything it can to maximise the potential of UK workers as well as making proposals for a continuation of a migrant labour scheme.
"It is not an understatement to say that SAWS has been the biggest contributory factor in the expansion and progression of horticulture in the UK in recent years by providing growers with a hardworking, flexible, well-educated migrant workforce.
"We need government to act swiftly in securing a successor to the SAWS scheme, so as to ensure a smooth transition after 2013.
"After all, growers can rise to the challenges of growing their crops but will fail if there is no labour for the harvest."
The call comes in response to a stark warning from Professor David Metcalf, chairman of the Government's Migration Advisory Committee (MAC).
He said: "There are 21,250 workers allowed into horticulture each year who can work for a maximum of six months. "It's a well-designed scheme, running since 2008 solely for Romanians and Bulgarians.
"In 2014, Romanians and Bulgarians will have completely free access to the labour market – will they decide instead to work in hotels, pubs and Tescos instead?
"Will there be enough people to pick the strawberries?"